Abstract 19129: Clinically Important Human Leukocyte Antibody Production is Uncommon in a Large Series of Pediatric Patients Supported with the Berlin Heart EXCOR Ventricular Assist Device
Background: Ventricular assist device (VAD) support is associated with human leukocyte (HLA) antibody production. This process, known as sensitization, has not been evaluated in pediatric patients supported with the Berlin Heart EXCOR VAD. Furthermore, the impact of sensitization in the era of single antigen assays for the detection of HLA antibodies is unclear.
Methods: The records of all patients supported with a Berlin Heart EXCOR VAD at our institution from 4/2005-8/2011 were reviewed. Class I and II HLA antibodies were identified by fluorescence methods pre-/post-VAD, with antibody titer reported as median fluorescence intensity (MFI). MFIs were summed to derive a total MFI for each patient post-VAD. To determine changes in HLA antibodies pre-/post-VAD, MFIs pre-VAD were compared with those ≥14 days post-VAD, but prior to transplant, using Wilcoxon matched-pairs sign-rank test. Sensitization was present if MFI for any antibody was > 1000 (threshold for a positive flow cytometric crossmatch).
Results: The Berlin Heart EXCOR VAD was used in 36 patients; 20 met inclusion criteria and 13 had complete MFI data. Median duration of support was 56 (21 - 131) days; all survived to transplant. For the entire group, changes in total MFI for class I and class II HLA antibodies were not significant over the course of VAD therapy. For class I antibodies, 6/13 (46%) were sensitized pre-VAD, and 7/13 (54%) were so for class II antibodies; sensitization was maintained for the same antibodies in 4/6 for class I antibodies and 5/7 for class II antibodies. De novo sensitization, including new antibodies in presensitized patients, occurred in 9/13 (69%) for class I antibodies and 4/13 (31%) for class II antibodies. Only one patient, however, had a positive flow cytometric crossmatch at transplant to one class II HLA antibody that developed on VAD. No patient was denied an acceptable donor heart on the basis of elevated HLA antibodies.
Conclusions: Using single antigen techniques, HLA sensitization is seen in approximately 50% of pediatric patients prior to initiating support with the Berlin Heart EXCOR VAD; nearly 70% developed de novo class I HLA antibodies on VAD. The clinical impact of such antibodies, however, appears to be limited in this population.
- © 2012 by American Heart Association, Inc.